1. Field of the Invention
This invention relates to a radio antenna and particularly an adjustable length, collapsible antenna with a loading coil.
2. Prior Art
Antennas, such as 1/4 wave vertical antennas, with impedance-matching or so-called "loading" coils are used with combination radio receiver and transmitter equipment and have become common in automotive use with the popularity of citizens-band transceivers. Typical antennas are in the form of a whip (solid rod) or tubular sections, and have either a base coil or a coil incorporated midway along the length of the antenna. Fine tuning of antennas has been accomplished by adjusting the length through clipping an end to shorten the length, or by adjusting an end portion that is telescoped relative to a carrying portion.
Since the presence of antennas of this type on vehicles often invites theft of the related radio equipment, it has become common to mount the antennas with clamps or the like to facilitate removal of the antenna by the owner, when the vehicle is not in use.
Heretofore, insofar as applicants are aware, no satisfactory antenna with a loading coil, suitable for use with citizens-band transceivers, has been available that is retractable or collapsible into concealment for automotive use. Collapsible antennas with coils are known, as are coil-carrying antennas that can be adjusted in length to modify performance; but known arrangements have failed to provide a citizens-band antenna that is both collapsible and adjustable in length, and in which a coil intermediate the ends of the antenna is concealed within support structure when the antenna is collapsed. Known arrangements of antennas with loading coils also have not been motor driven between extended and retracted positions.